Elongated threaded fasteners or connectors are known to have external threads at one or both ends and a flange section intermediate the ends in a hex configuration similar to a nut by which the fastener can be rotated. For example, FIGS. 1, 2 and 3 illustrate prior art connectors for an oil cooler installation in an automobile. The connector is a one-piece body 10 including threaded portions 12, 14 at opposite ends thereof which may cover the entire surface of a cylindrical portion of body 10, or only parts thereof as necessary for the final installation and use. A flange 16 is provided between threads 12 and 14, and in the exemplary embodiment of the prior art includes a washer portion 18 and a nut-like hex portion 20 by which connector 10 can be engaged with tools such as wrenches for rotating the connector.
As known in the prior art, connector 10 is formed as a one-piece body in a cold forming technique. The connector is adapted to mate with two mating components, with a first component 22 threadedly received on threads 12 and the second component (not shown) threadedly received on threads 14. Hex portion 20 is used to rotate the connector with a tool (not shown) when assembling the connector to one or both of the components.
After cold forming the basic shape of the connector, threads 12 and 14 are machined at opposite ends. When machining thread 12 adjacent hex portion 20, given the manufacturing process, the thread cannot be threaded all the way to the top of the hex. An intermediate segment 24 remains, which is not threaded and is of a diameter slightly larger than the root diameter between threads of the threaded portion. A chamfer-like curved portion 24 remains between the end of the thread and the top of the hex formation. The chamfer is the result of not being able to generate a complete thread against a wall of material, such as the top of the hex formation. Accordingly, without removing the chamfer or radius, the mating part, which typically does not include a lead-in chamfer, does not fit tightly against the hex because of the interference of the chamfer or radius portion 24.
Solutions for the above described problem have been addressed in two different ways. As illustrated in FIG. 2, a washer 26 can be interposed between the confronting surfaces of hex portion 20 and first component 22. Washer 26 is of sufficient thickness to fill the axial distance equivalent to the height of chamfer portion 24. While solving the problem of establishing a tight connection between connector 10 and component 22, the use of a washer adds an additional part to the assembly, increasing costs, extending assembly time and creating a source of possible improper assembly if washer 26 is omitted inadvertently.
FIG. 3 illustrates another known solution in the prior art to allow tight assembly of component 22 against hex portion 20 on connector 10. The chamfer portion 24 is machined away to provide an undercut 28 between the last thread 12 and the surface of hex portion 20. While not shown for reasons of clarity in FIG. 3, component 22 can be threaded tightly against the end surface of hex portion 20 in the structure of FIG. 3. This solves the problem but adds undesirable manufacturing cost to component 10 by requiring an additional machining step.
What is needed is a connector that can be manufactured efficiently and cost-effectively by known manufacturing techniques and that can be installed in a final assembly quickly and easily.